Current transformation technology provides an opportunity to engineer plants with desired traits. Major advances in plant transformation have occurred over the last few years. However, most transformation methods rely on the introduction of polynucleotides into embryonic tissues that are rapidly proliferating. Methods that allow for the transformation of more mature tissues would save considerable time and money. Accordingly, methods are needed in the art to increase transformation efficiencies of plants and allow for the transformation of more mature tissues.
Further, it is often necessary to reduce the activity of a transgene because the transgene may negatively affect the growth or fertility of the plant. Recombination systems can be used to excise the transgene, wherein the expression of a site-specific recombinase is regulated by an inducible promoter. Often, these systems are associated with premature excision. Accordingly, methods are needed in the art to efficiently excise transgenes with limited premature excision.